A Plane-Dependent Model of 3D Grid Cells for Representing Both 2D and 3D Spaces Under Various Navigation Modes

Grid cells are crucial in path integration and representation of the external world. The spikes of grid cells spatially form clusters called grid fields, which encode important information about allocentric positions. To decode the information, studying the spatial structures of grid fields is a key task for both experimenters and theorists. Experiments reveal that grid fields form hexagonal lattice during planar navigation, and are anisotropic beyond planar navigation. During volumetric navigation, they lose global order but possess local order. How grid cells form different field structures behind these different navigation modes remains an open theoretical question. However, to date, few models connect to the latest discoveries and explain the formation of various grid field structures. To fill in this gap, we propose an interpretive plane-dependent model of three-dimensional (3D) grid cells for representing both two-dimensional (2D) and 3D space. The model first evaluates motion with respect to planes, such as the planes animals stand on and the tangent planes of the motion manifold. Projection of the motion onto the planes leads to anisotropy, and error in the perception of planes degrades grid field regularity. A training-free recurrent neural network (RNN) then maps the processed motion information to grid fields. We verify that our model can generate regular and anisotropic grid fields, as well as grid fields with merely local order; our model is also compatible with mode switching. Furthermore, simulations predict that the degradation of grid field regularity is inversely proportional to the interval between two consecutive perceptions of planes. In conclusion, our model is one of the few pioneers that address grid field structures in a general case. Compared to the other pioneer models, our theory argues that the anisotropy and loss of global order result from the uncertain perception of planes rather than insufficient training.

Download Full-text

Gold Exploration in Two and Three Dimensions: Improved and Correlative Insights from Microscopy and X-Ray Computed Tomography

Minerals ◽

10.3390/min10050476 ◽

2020 ◽

Vol 10 (5) ◽

pp. 476

Author(s):

Joshua Chisambi ◽

Bjorn von der Heyden ◽

Muofhe Tshibalanganda ◽

Stephan Le Roux

Keyword(s):

Computed Tomography ◽

Spatial Distribution ◽

Gold Mineralization ◽

Three Dimensional ◽

Three Dimensions ◽

Low Grade ◽

X Ray ◽

3D Space ◽

X Ray Computed ◽

2D And 3D

In this contribution, we highlight a correlative approach in which three-dimensional structural/positional data are combined with two dimensional chemical and mineralogical data to understand a complex orogenic gold mineralization system; we use the Kirk Range (southern Malawi) as a case study. Three dimensional structures and semi-quantitative mineral distributions were evaluated using X-ray Computed Tomography (XCT) and this was augmented with textural, mineralogical and chemical imaging using Scanning Electron Microscopy (SEM) and optical microscopy as well as fire assay. Our results detail the utility of the correlative approach both for quantifying gold concentrations in core samples (which is often nuggety and may thus be misrepresented by quarter- or half-core assays), and for understanding the spatial distribution of gold and associated structures and microstructures in 3D space. This approach overlays complementary datasets from 2D and 3D analytical protocols, thereby allowing a better and more comprehensive understanding on the distribution and structures controlling gold mineralization. Combining 3D XCT analyses with conventional 2D microscopies derive the full value out of a given exploration drilling program and it provides an excellent tool for understanding gold mineralization. Understanding the spatial distribution of gold and associated structures and microstructures in 3D space holds vast potential for exploration practitioners, especially if the correlative approach can be automated and if the resultant spatially-constrained microstructural information can be fed directly into commercially available geological modelling software. The extra layers of information provided by using correlative 2D and 3D microscopies offer an exciting new tool to enhance and optimize mineral exploration workflows, given that modern exploration efforts are targeting increasingly complex and low-grade ore deposits.

Download Full-text

2D and 3D Shape Sensing Based on 7-Core Fiber Bragg Gratings

Photonic Sensors ◽

10.1007/s13320-020-0579-0 ◽

2020 ◽

Vol 10 (4) ◽

pp. 306-315

Author(s):

Tianting Lai ◽

Pu Cheng ◽

Congliao Yan ◽

Chi Li ◽

Wenbin Hu ◽

...

Keyword(s):

Three Dimensional ◽

Fiber Bragg Gratings ◽

Bragg Gratings ◽

Shape Reconstruction ◽

Two Dimensional ◽

3D Shape ◽

3D Space ◽

Core Fiber ◽

Shape Sensing ◽

2D And 3D

Abstract A fiber-optic shape sensing based on 7-core fiber Bragg gratings (FBGs) is proposed and experimentally demonstrated. The investigations are presented for two-dimensional and three-dimensional shape reconstruction by distinguishing bending and twisting of 7-core optical fiber with FBGs. The curvature and bending orientation can be calculated by acquiring FBG wavelengths from any two side cores among the six outer cores. And the shape sensing in three-dimensional (3D) space is computed by analytic geometry theory. The experiments corresponding of two-dimensional (2D) and 3D shape sensing are demonstrated and conducted to verify the theoretical principles. The resolution of curvature is about 0.1m−1 for 2D measuring. The error of angle in shape reconstruction is about 1.89° for 3D measuring. The proposed sensing technique based on 7-core FBGs is promising of high feasibility, stability, and repeatability, especially for the distinguishing ability on the bending orientation due to the six symmetrical cores on the cross-section.

Download Full-text

Linear and Nonlinear Random Walks in 1d, 2d and 3d Space.

10.46940/gjaap.01.1001 ◽

2019 ◽

pp. 1-2

Keyword(s):

Random Walk ◽

Three Dimensional ◽

Ancient Egypt ◽

Regular Octahedron ◽

Visual Model ◽

3D Space ◽

Visual Models ◽

Equilateral Triangles ◽

Linear And Nonlinear ◽

2D And 3D

The regular octahedron [1] refers to the number of five Platonic figures. It can be composed of eight equal equilateral triangles or twelve identical segments. "The octahedron is dual to the cube" [2]. The regular octahedron can also be composed of many identical small cubes just as in Ancient Egypt were pyramids of stone blocks. The construction of an octahedron using small cubes can be obtained by considering a random walk in three-dimensional (3D) space. In [3] we considered a visual model of a 3D random linear and nonlinear walk in an octahedron. In [3,4] we reviewed and systematized the visual models of 1D, 2D and 3D random linear and nonlinear walks too.

Download Full-text

Simplified electromagnetic actuation system for three dimensional locomotive and drilling microrobot

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406214558473 ◽

2014 ◽

Vol 229 (13) ◽

pp. 2443-2454 ◽

Cited By ~ 2

Author(s):

Hyunchul Choi ◽

Semi Jeong ◽

Cheong Lee ◽

Gwangjun Go ◽

Jin Zhen ◽

...

Keyword(s):

Performance Test ◽

Three Dimensional ◽

External Electromagnetic Field ◽

Electromagnetic Actuation ◽

Drilling Performance ◽

3D Space ◽

Cell Based Therapy ◽

Actuation System ◽

Electromagnetic Actuation System ◽

2D And 3D

Many researchers have studied and developed various types of medical microrobots using an external electromagnetic field and a permanent magnet. Most microrobots are very small and remotely controlled. Their medical applications include minimally invasive surgery (MIS), capsule endoscopy, drug delivery system (DDS), and cell based therapy. Two-dimensional (2D) or 3D locomotion of microrobots using different electromagnetic actuation (EMA) systems has been studied. In this paper, we propose a simplified EMA system having the same functions as our previous proposed EMA system. Because the simplified EMA system has a smaller coils structure, it consumes less power than the previous EMA system. First, through basic locomotive tests, we demonstrate that the microrobot using the proposed EMA system can move along a desired path in 2D and 3D space. Second, a drilling performance test was carried out on the microrobot. Finally, through quantitative comparison, it was verified that the proposed EMA system consumed 58% less power than the previous EMA system.

Download Full-text

Design, Fabrication, and Testing of a Novel 3D 3-Fingered Electrothermal Microgripper with Multiple Degrees of Freedom

Micromachines ◽

10.3390/mi12040444 ◽

2021 ◽

Vol 12 (4) ◽

pp. 444

Author(s):

Guoning Si ◽

Liangying Sun ◽

Zhuo Zhang ◽

Xuping Zhang

Keyword(s):

Degrees Of Freedom ◽

Dynamic Properties ◽

Three Dimensional ◽

Polyimide Film ◽

Zebrafish Embryos ◽

Multiple Degrees Of Freedom ◽

Electrothermal Actuator ◽

3D Space ◽

Pick And Place

This paper presents the design, fabrication, and testing of a novel three-dimensional (3D) three-fingered electrothermal microgripper with multiple degrees of freedom (multi DOFs). Each finger of the microgripper is composed of a V-shaped electrothermal actuator providing one DOF, and a 3D U-shaped electrothermal actuator offering two DOFs in the plane perpendicular to the movement of the V-shaped actuator. As a result, each finger possesses 3D mobilities with three DOFs. Each beam of the actuators is heated externally with the polyimide film. The durability of the polyimide film is tested under different voltages. The static and dynamic properties of the finger are also tested. Experiments show that not only can the microgripper pick and place microobjects, such as micro balls and even highly deformable zebrafish embryos, but can also rotate them in 3D space.

Download Full-text

Homogeneous 2D and 3D alignment of cardiomyocyte in dilated cardiomyopathy revealed by intravital heart imaging

Scientific Reports ◽

10.1038/s41598-021-94100-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kiyoshi Masuyama ◽

Tomoaki Higo ◽

Jong-Kook Lee ◽

Ryohei Matsuura ◽

Ian Jones ◽

...

Keyword(s):

Heart Failure ◽

Dilated Cardiomyopathy ◽

Cardiac Dysfunction ◽

Three Dimensional ◽

Single Layer ◽

Specific Pattern ◽

Two Dimensional ◽

Heart Imaging ◽

Novel Method ◽

2D And 3D

AbstractIn contrast to hypertrophic cardiomyopathy, there has been reported no specific pattern of cardiomyocyte array in dilated cardiomyopathy (DCM), partially because lack of alignment assessment in a three-dimensional (3D) manner. Here we have established a novel method to evaluate cardiomyocyte alignment in 3D using intravital heart imaging and demonstrated homogeneous alignment in DCM mice. Whilst cardiomyocytes of control mice changed their alignment by every layer in 3D and position twistedly even in a single layer, termed myocyte twist, cardiomyocytes of DCM mice aligned homogeneously both in two-dimensional (2D) and in 3D and lost myocyte twist. Manipulation of cultured cardiomyocyte toward homogeneously aligned increased their contractility, suggesting that homogeneous alignment in DCM mice is due to a sort of alignment remodelling as a way to compensate cardiac dysfunction. Our findings provide the first intravital evidence of cardiomyocyte alignment and will bring new insights into understanding the mechanism of heart failure.

Download Full-text

Do 3D Face Images Capture Cues of Strength, Weight, and Height Better than 2D Face Images do?

Adaptive Human Behavior and Physiology ◽

10.1007/s40750-021-00170-8 ◽

2021 ◽

Vol 7 (3) ◽

pp. 209-219

Author(s):

Iris J Holzleitner ◽

Alex L Jones ◽

Kieran J O’Shea ◽

Rachel Cassar ◽

Vanessa Fasolt ◽

...

Keyword(s):

Three Dimensional ◽

Physical Characteristics ◽

Two Dimensional ◽

3D Images ◽

3D Face ◽

Face Images ◽

Similar Accuracy ◽

2D And 3D ◽

2D Images ◽

Better Than

Abstract Objectives A large literature exists investigating the extent to which physical characteristics (e.g., strength, weight, and height) can be accurately assessed from face images. While most of these studies have employed two-dimensional (2D) face images as stimuli, some recent studies have used three-dimensional (3D) face images because they may contain cues not visible in 2D face images. As equipment required for 3D face images is considerably more expensive than that required for 2D face images, we here investigated how perceptual ratings of physical characteristics from 2D and 3D face images compare. Methods We tested whether 3D face images capture cues of strength, weight, and height better than 2D face images do by directly comparing the accuracy of strength, weight, and height ratings of 182 2D and 3D face images taken simultaneously. Strength, height and weight were rated by 66, 59 and 52 raters respectively, who viewed both 2D and 3D images. Results In line with previous studies, we found that weight and height can be judged somewhat accurately from faces; contrary to previous research, we found that people were relatively inaccurate at assessing strength. We found no evidence that physical characteristics could be judged more accurately from 3D than 2D images. Conclusion Our results suggest physical characteristics are perceived with similar accuracy from 2D and 3D face images. They also suggest that the substantial costs associated with collecting 3D face scans may not be justified for research on the accuracy of facial judgments of physical characteristics.

Download Full-text

Extracellular vesicles from three dimensional culture of human placental mesenchymal stem cells ameliorated renal ischemia/reperfusion injury

The International Journal of Artificial Organs ◽

10.1177/0391398820986809 ◽

2021 ◽

pp. 039139882098680

Author(s):

Xuefeng Zhang ◽

Nan Wang ◽

Yuhua Huang ◽

Yan Li ◽

Gang Li ◽

...

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Extracellular Vesicles ◽

Therapeutic Potential ◽

Expression Profiles ◽

Ischemia Reperfusion ◽

Three Dimensional ◽

3D Culture ◽

Placental Mesenchymal Stem Cells ◽

2D And 3D

Background: Three-dimensional (3D) culture has been reported to increase the therapeutic potential of mesenchymal stem cells (MSCs). The present study assessed the therapeutic efficacy of extracellular vesicles (EVs) from 3D cultures of human placental MSCs (hPMSCs) for acute kidney injury (AKI). Methods: The supernatants from monolayer culture (2D) and 3D culture of hPMSCs were ultra-centrifuged for EVs isolation. C57BL/6 male mice were submitted to 45 min bilateral ischemia of kidney, followed by renal intra-capsular administration of EVs within a 72 h reperfusion period. Histological, immunohistochemical, and ELISA analyses of kidney samples were performed to evaluate cell death and inflammation. Kidney function was evaluated by measuring serum creatinine and urea nitrogen. The miRNA expression profiles of EVs from 2D and 3D culture of hPMSCs were evaluated using miRNA microarray analysis. Results: The 3D culture of hPMSCs formed spheroids with different diameters depending on the cell density seeded. The hPMSCs produced significantly more EVs in 3D culture than in 2D culture. More importantly, injection of EVs from 3D culture of hPMSCs into mouse kidney with ischemia-reperfusion (I/R)-AKI was more beneficial in protecting from progression of I/R than those from 2D culture. The EVs from 3D culture of hPMSCs were more efficient against apoptosis and inflammation than those from 2D culture, which resulted in a reduction in tissue damage and amelioration of renal function. MicroRNA profiling analysis revealed that a set of microRNAs were significantly changed in EVs from 3D culture of hPMSCs, especially miR-93-5p. Conclusion: The EVs from 3D culture of hPMSCs have therapeutic potential for I/R-AKI.

Download Full-text

Value of Three-Dimensional Digital Subtraction Angiography for Detection and Classification of Intracranial Aneurysm Remnants After Clipping

Operative Neurosurgery ◽

10.1093/ons/opab087 ◽

2021 ◽

Author(s):

Serge Marbacher ◽

Matthias Halter ◽

Deborah R Vogt ◽

Jenny C Kienzler ◽

Christian T J Magyar ◽

...

Keyword(s):

Intracranial Aneurysm ◽

Digital Subtraction Angiography ◽

Diagnostic Yield ◽

Three Dimensional ◽

P Value ◽

Digital Subtraction ◽

Patient Demographics ◽

Included Patient ◽

2D And 3D

Abstract BACKGROUND The current gold standard for evaluation of the surgical result after intracranial aneurysm (IA) clipping is two-dimensional (2D) digital subtraction angiography (DSA). While there is growing evidence that postoperative 3D-DSA is superior to 2D-DSA, there is a lack of data on intraoperative comparison. OBJECTIVE To compare the diagnostic yield of detection of IA remnants in intra- and postoperative 3D-DSA, categorize the remnants based on 3D-DSA findings, and examine associations between missed 2D-DSA remnants and IA characteristics. METHODS We evaluated 232 clipped IAs that were examined with intraoperative or postoperative 3D-DSA. Variables analyzed included patient demographics, IA and remnant distinguishing characteristics, and 2D- and 3D-DSA findings. Maximal IA remnant size detected by 3D-DSA was measured using a 3-point scale of 2-mm increments. RESULTS Although 3D-DSA detected all clipped IA remnants, 2D-DSA missed 30.4% (7 of 23) and 38.9% (14 of 36) clipped IA remnants in intraoperative and postoperative imaging, respectively (95% CI: 30 [ 12, 49] %; P-value .023 and 39 [23, 55] %; P-value = <.001), and more often missed grade 1 (< 2 mm) clipped remnants (odds ratio [95% CI]: 4.3 [1.6, 12.7], P-value .005). CONCLUSION Compared with 2D-DSA, 3D-DSA achieves a better diagnostic yield in the evaluation of clipped IA. Our proposed method to grade 3D-DSA remnants proved to be simple and practical. Especially small IA remnants have a high risk to be missed in 2D-DSA. We advocate routine use of either intraoperative or postoperative 3D-DSA as a baseline for lifelong follow-up of clipped IA.

Download Full-text

Two-dimensional-Wilkins and real-time transesophageal three-dimensional scoring systems: Which one is preferred to mitral valve morphological assessment?

Asian Cardiovascular and Thoracic Annals ◽

10.1177/02184923211030424 ◽

2021 ◽

pp. 021849232110304

Author(s):

Mehrnoush Toufan ◽

Zahra Jabbary ◽

Naser Khezerlou aghdam

Keyword(s):

Mitral Valve ◽

Transthoracic Echocardiography ◽

Scoring System ◽

Three Dimensional ◽

Scoring Systems ◽

Two Dimensional ◽

Mitral Valve Area ◽

2D And 3D ◽

Morphological Assessment ◽

Valve Area

Background To quantify valvular morphological assessment, some two-dimensional (2D) and three-dimensional (3D) scoring systems have been developed to target the patients for balloon mitral valvuloplasty; however, each scoring system has some potential limitations. To achieve the best scoring system with the most features and the least restrictions, it is necessary to check the degree of overlap of these systems. Also the factors related to the accuracy of these systems should be studied. We aimed to determine the correlation between the 2D Wilkins and real-time transesophageal three-dimensional (RT3D-TEE) scoring systems. Methods This cross-sectional study was performed on 156 patients with moderate to severe mitral stenosis who were candidates for percutaneous balloon valvuloplasty. To morphologic assessment of mitral valve, patients were examined by 2D-transthoracic echocardiography and RT3D-TEE techniques on the same day. Results A strong association was found between total Wilkins and total RT3D-TEE scores (r = 0.809, p < 0.001). The mean mitral valve area assessed by the 2D and 3D was 1.07 ± 0.25 and 1.03 ± 0.26, respectively, indicating a mean difference of 0.037 cm2 (p = 0.001). We found a strong correlation between the values of mitral valve area assessed by 2D and 3D techniques (r = 0.846, p < 0.001). Conclusion There is a high correlation between the two scoring systems in terms of evaluating dominant morphological features. Partially, mitral valve area overestimation in the 2D-transthoracic echocardiography and its inability to assess commissural involvement as well as its dependence on patient age were exceptions in this study.

Download Full-text